Field of the Invention
The invention relates to an electronic device, and particularly to an electronic device and a method for adjustment of a projecting screen of an electronic device.
Description of Related Art
Projection apparatuses are being widely used often in a meeting room, in a classroom or at home nowadays. When a projector is used for display purposes, a dark environment is required for clear presentation. However, creating such dark environment is inconvenient in various respects. One main reason is that a conventional screen for projection is a flat surface good in light scattering since the screen projects light from all sources outward in all directions, no matter the light is from the projector or other illumination light sources or ambient light sources. Thus, to aim for a clear projected screen, it is necessary to control the light sources other than the projector. Projectors on the market are classified into LCD projectors and DLP projectors. An LCD projector uses three liquid-crystal panels respectively as imaging elements of three primary colors including red, green and blue. After the light from a light source is converted into monochromatic lights by a color separation unit, the monochromatic lights then reach their corresponding liquid-crystal panels, and the three liquid-crystal panels control brightness of light passed according to colors of pixel points. Finally, the light passes through a light-focusing unit to be projected to the screen and the lights from the three liquid-crystal panels converge to form a pixel point. A DLP projector has only one DMD imaging member. The light from a light source undergoes color separation by a color wheel and then reaches the DMD in a time-division manner. Rotation of an upper micromirror of the DMD is controlled according to colors of pixel points. The lights of three colors reach the screen in a time-division manner and the screen is formed thereby. Though the DLP projector has better contrast presentation, the DLP projector does not always achieve a high contrast ratio under the influence of an ambient light source. In order to improve projection quality, a user may manually make adjustments by using brightness and contrast options in the projector. Nonetheless, such method causes more inconvenience to the user.